Role of Chest Computed Tomography in Patients Hospitalized with Community-Acquired Complicated Parapneumonic Effusion or Empyema

Background: Data regarding predictors of the outcome in patients with community-acquired complicated parapneumonic effusion (CPPE) or empyema are insufficient. The aim of the present study was to investigate the prognostic factors in these patients. Methods: Patients with community-acquired pneumonia (CAP) were classified into a CPPE or empyema group and a control group. The patients with CPPE or empyema were further divided into longer and shorter length of stay (LOS) groups, and clinical variables and computed tomographic (CT) findings were compared between the 2 groups. Results: Of outcome variables, LOS was significantly longer in the CPPE or empyema group than in the control group (13 days [interquartile range, 10‒17 days] versus 8 days [6‒12 days], p < 0.001), whereas 30-day mortality and in-hospital mortality were not significantly different between the 2 groups. Patients with CPPE or empyema were divided into shorter LOS (<14 days) and longer LOS (≥14 days) groups. Pneumonia severity index (PSI) class IV‒V (odds ratio [OR], 2.79; 95% confidence interval [CI]: 1.35, 5.76; p = 0.006), increased attenuation of extrapleural fat (OR, 2.26; 95% CI: 1.06, 4.80; p = 0.034), and pleural microbubbles (OR 3.93; 95% CI: 1.03, 14.98; p = 0.045) were independent predictors for prolonged LOS in CAP patients with CPPE or empyema. Conclusions: Increased attenuation of extrapleural fat and pleural microbubbles assessed with CT and PSI class IV‒V independently predicted prolonged LOS in CAP patients with CPPE or empyema. These findings may be helpful to identify patients who need more intensive evaluation and intervention.